This invention concerns the field of electrical energy transmission lines and especially the variety of radio frequency energy transmission lines known as microstrip lines as are often used within integrated circuit electronic devices.
Even though transmission line dielectric energy losses are known to increase at higher operating frequencies, a major component of microstrip transmission line loss remains in conductor energy dissipation when the transmission line is used at microwave, millimeter wave and higher frequencies. Since these conductor losses increase as the current density increases in a transmission line conductor, the known phenomenon of skin effect conduction and the resulting current crowding in a conductor can have significant influence on line losses occurring in higher frequency applications. The present invention demonstrates, however, that these conductor related energy losses may be controlled through use of transmission line conductors disposed in skin effect-considered configurations.
The U.S. patent art indicates the presence of significant inventive activity in the area of transmission lines and their loss-considered radio frequency operation. Patent in this art are, for example, concerned with the skin effect phenomenon and with combinations of this phenomenon with ground planes, integrated circuits and loss-considered structures. The use of circular configurations in transmission line conductors is also shown in certain of these patents.
None of these patents is, however, understood to disclose the extensively rounded bulbous shape for a transmission line conductor of a microstrip or related type of transmission line that is disclosed in the present invention nor the high radio frequency energy and loss-related considerations which support use of this shape.